Appendix E: Probe Selection
TDS 684A, TDS 744A, & TDS 784A User Manual E–5
Optical Probes
Optical probes let you blend the functions of an optical power meter with the
high-speed analog waveform analysis capability of an oscilloscope. You have the
capability of acquiring, displaying, and analyzing optical and electrical signals
simultaneously.
Applications include measuring the transient optical properties of lasers, LEDs,
electro-optic modulators, and flashlamps. You can also use these probes in the
development, manufacturing, and maintenance of fiber optic control networks,
local area networks (LANs), fiber-based systems based on the FDDI and SONET
standard, optical disk devices, and high-speed fiber optic communications
systems.
NOTE. When you connect any probe with a TEKPROBE (level 2) interface to the
oscilloscope, the input impedance of the oscilloscope automatically becomes
50 . If you then connect a high input impedance passive probe you need to set
the input impedance back to 1 M. The procedure To Change Vertical Parame-
ters, on page 3–12, explains how to change the input impedance.
Time-to-Voltage Converter
The instantaneous time-interval to voltage converter (TVC) continuously
converts consecutive timing measurements to a time-interval versus time
waveform.
Timing variations typically appear as left-to-right motion, or jitter, on an
oscilloscope. Time base or trigger holdoff adjustments may improve display
stability, but they do not show timing dynamics. The TVC untangles the often
confusing waveforms and delivers a coherent real-time view.
The TVC adds three measurement functions to the voltage versus time capability
of your oscilloscope: time delay versus time, pulse-width versus time, and period
versus time.